Testing the Role of Climate Change in Species Decline: Is the Eastern Quoll a Victim of a Change in the Weather?

To conserve a declining species we first need to diagnose the causes of decline. This is one of the most challenging tasks faced by conservation practitioners. In this study, we used temporally explicit species distribution models (SDMs) to test whether shifting weather can explain the recent decline of a marsupial carnivore, the eastern quoll (Dasyurus viverrinus). We developed an SDM using weather variables matched to occurrence records of the eastern quoll over the last 60 years, and used the model to reconstruct variation through time in the distribution of climatically suitable range for the species. The weather model produced a meaningful prediction of the known distribution of the species. Abundance of quolls, indexed by transect counts, was positively related to the modelled area of suitable habitat between 1990 and 2004. In particular, a sharp decline in abundance from 2001 to 2003 coincided with a sustained period of unsuitable weather over much of the species’ distribution. Since 2004, abundance has not recovered despite a return to suitable weather conditions, and abundance and area of suitable habitat have been uncorrelated. We suggest that fluctuations in weather account for the species’ recent decline, but other unrelated factors have suppressed recovery.     

Managing Feral Cats on a University's Campuses: How Many Are There and Is Sterilization Having an Effect?

Worldwide domestic and feral cat (Felis catus) numbers have increased. Concerns regarding high populations of feral cats in urban areas include wildlife predation, public nuisance, and disease. This study aimed to estimate the size of the feral cat population on 5 campuses of the University of KwaZulu-Natal, South Africa, to determine whether sterilization has an effect and to make management recommendations. The study used both the total count and mark-recapture methods to estimate the feral cat population on each campus. The study chose a noninvasive method of taking photographs to “mark” individuals and record those who were sterilized. The study estimated a total of 186 cats on all campuses and density at 161 cats km^?2. There was a negative relationship between sterilization and numbers. Sites with higher sterilization showed a lower proportion of younger cats. At the average sterilization of 55%, the population, according to predictions, would remain stable at fecundity, survival, and immigration rates reported by cat caretakers. However, caretakers underestimated cat abundance by 7 ± 37 SD%. Caretakers' feral cat sterilization and feeding programs appear to provide a service to the university community. Key management recommendations were to increase sterilization to 90% to reduce the population over the long term and to raise funds to support the costs incurred by voluntary cat caretakers.     

Is There a Bias Against Stray Cats in Shelters? People's Perception of Shelter Cats and How It Influences Adoption Time

The determination of adoptability is a fundamental issue facing shelters wishing to rehome cats. Many shelters in the United States cannot keep a cat indefinitely and increased time in the shelter environment may lead to reduced animal welfare due to chronic stress or euthanasia. In a series of studies, we examined whether entry type (whether a cat came to the shelter as an owner-surrendered or stray) as well as a cat's perceived social behavior influenced adoption times and people's ratings of adoptability. In study 1, we used archival data from 1,089 cats in a Midwest shelter and found that owner-surrendered cats were adopted significantly sooner than stray cats. In study 2, we further explored the difference between owner-surrendered and stray cats by measuring the social behavior of 56 shelter cats and their time before adoption. Similarly, we found in this sample that owner-surrendered cats were adopted on average nine days sooner than stray cats. Hierarchical regression analysis indicated that entry type was a significant predictor of days to adopt, and that latency to approach a human significantly improved the prediction model. Further, how quickly stray cats, but not owner-surrendered cats, approached a human experimenter correlated significantly with a shortened adoption time in the actual adoption scenario. Finally, in study 3, we used an on-line survey to present 12 dual-image pictures of cats and manipulated whether the information about the cat listed each as owner-surrendered or stray cat. We asked 120 college students to rate their likelihood of adopting each pictured cat. When participants were asked about reasons they would adopt a particular cat, 81% reported friendly behavior toward them; yet when viewing the mirror images in the survey (no behavioral information available), cats received higher adoptability ratings when presented as owner-surrendered compared with the flipped image of that cat presented as a stray. Taken together, these studies suggest that adopters' perception of stray cats, as well as cats' interactions with humans, influence the amount of time a cat remains in the shelter prior to adoption.     

Materialism and Sensuality: Visualizing the Devil in the Festival of Our Lady of Urkupiña

During the Festival of Our Lady of Urkupin ¨ a, held every August in Quillacollo, Bolivia, an estimated half million pilgrims petition Our Lady for wealth and material goods. The festival has become a national event and now includes the participation of government officials, including the President, as well as widespread coverage by the media. The festival has also become a point of controversy and contestation over the meanings of Bolivian nationalism, commercialism, and economic development. These issues, as I will show, have been articulated through criticisms of the festival as being too sensuous and overly commercialized. Through an examination of media coverage of the festival of Urkupiña, this article focuses on the ways that "evils" of materialism and sensuality are represented visually. The Bolivian state and the Catholic Church have sought to define the meaning of the festival in terms of devotion and national identity while criticizing some festival practices associated with gaining wealth. Here I show how the folkloric and devotional elements of the festival are embodied in the dancers while the visual referent for the materialism of the festival is street vendors. I also discuss how the festival transforms the meanings of the ch'alla and other Andeanpractices that anthropologists have traditionally associated with resistance to capitalism (as found for example in the work of June Nash and Michael Taussig). The article concludes by noting that, rather than mapping these meanings ontogeneralized resistance, anthropologists must be prepared fully to engage contestations over devotion, material gain, sensuousness, and economic development. In short, we should also be prepared to dance with the devil.     

Not the End of the World? Post-Classical Decline and Recovery in Rural Anatolia

Between the foundation of Constantinople as capital of the eastern half of the Roman Empire in 330 CE and its sack by the Fourth Crusade in 1204 CE, the Byzantine Empire underwent a full cycle from political-economic stability, through rural insecurity and agrarian decline, and back to renewed prosperity. These stages plausibly correspond to the phases of over-extension (K), subsequent release (Ω) and recovery (α) of the Adaptive Cycle in Socio-Ecological Systems. Here we track and partly quantify the consequences of those changes in different regions of Anatolia, firstly for rural settlement (via regional archaeological surveys) and secondly for land cover (via pollen analysis). We also examine the impact of climate changes on the agrarian system. While individual histories vary, the archaeological record shows a major demographic decline between ca .650 and ca. 900 CE in central and southwestern Anatolia, which was then a frontier zone between Byzantine and Arab armies. In these regions, and also in northwest Anatolia, century-scale trends in pollen indicate a substantial decline in the production of cereal and tree crops, and a smaller decline in pastoral activity. During the subsequent recovery (α) phase after 900 CE there was strong regional differentiation, with central Anatolia moving to a new economic system based on agro-pastoralism, while lowland areas of northern and western Anatolia returned to the cultivation of commercial crops such as olive trees. The extent of recovery in the agrarian economy was broadly predictable by the magnitude of its preceding decline, but the trajectories of recovery varied between different regions.     

Changes in Stream Primary Producer Communities Resulting from Large-Scale Catastrophic Amphibian Declines: Can Small-Scale Experiments Predict Effects of Tadpole Loss?

Global declines of amphibian populations are well documented, yet effects of these declines on freshwater ecosystem structure and function are poorly understood. Here we examine responses of algal primary producers to tadpole extirpation over differing spatial and temporal scales. We experimentally excluded tadpoles from artificial substrata within localized areas (0.25 m²) of two streams. One stream had an intact community of frogs (frog stream), and the other had recently experienced a catastrophic decline (frogless stream), leaving virtually no tadpoles. In the frog stream, there were significantly greater levels of chlorophyll a (+111%, P = 0.009), ash-free dry mass (AFDM) (+163%, P = 0.02), inorganic sediments (+114%, P = 0.001), and higher mean algal cell biovolume in tadpole exclusion treatments than in the tadpole access treatments. Correspondingly, overall AFDM-specific net primary production (NPP) increased by 38% (P = 0.001) and chlorophyll a-specific NPP increased by 29% (P = 0.001) in tadpole access treatments compared to tadpole exclusion treatments. Areal-specific NPP did not differ between treatments. There were no significant differences in chlorophyll a, AFDM, inorganic sediments, algal cell biovolume, or biomass-specific NPP between treatments in the frogless stream. Fifteen months after our experiments, a massive amphibian decline associated with a fungal pathogen occurred in the frog stream, resulting in the extirpation of over 90% of tadpoles. This extirpation was followed by significant increases in levels of chlorophyll a (269%, P = 0.001), AFDM (+220%, P < 0.001), and inorganic sediments (+140%, P = 0.001). Reach-scale NPP increased from −1587 to −810 mg DO m⁻² d⁻¹. Additionally, algal community composition shifted from a dominance of small adnate diatoms (pre-decline) to a dominance of large upright algal species (post-decline). Our experimental results, combined with algal monitoring at the reach scale, indicate that over the course of our study catastrophic amphibian losses have significant effects on stream ecosystem structure and function. Ecosystem-level impacts of tadpole extirpations were more dramatic than results from our small-scale, short-term experiments, which predicted the direction of change in response variables but underestimated the magnitude. However, the long-term stream ecosystem responses remain unknown. Author Contributions: S.C., C.M.P., M.R.W., K.R.L., and S.K. designed the study, S.C., C.M.P., R.B., M.R.W., K.R.L., and A.D.H. performed research, S.C., C.M.P., R.J.B., M.R.W., and A.D.H. analyzed data. S.C., C.M.P., and R.J.B. wrote the paper.     

Is extinction the hallmark of operant discrimination?: Reinforcement and S effects

Using a successive discrimination procedure with rats, three experiments investigated the contribution of reinforcement rate and amount of S(Delta) exposure on the acquisition of an operant discrimination. S(D) components and were always 2 min in length, while S(Delta) (extinction) components were either 1 min or 4 min in length; responses in S(D) were reinforced on one of four schedules. In Experiment 1, each of eight groups were exposed to one possible combination of rate of reinforcement and S(Delta) component length. At every level of reinforcement, the 4 min S(Delta) groups acquired the discrimination more quickly. However, within each level of reinforcement, the proportions of responding in S(D) as a function cumulative S(Delta) exposure were equivalent, regardless of the number of reinforcers earned in S(D), suggesting that extinction is the "hallmark" of discrimination. Experiment 2 sought to replicate these results in a within-subjects design, and although the 4 min S(Delta) conditions always produced superior discriminations, the lack of discriminated responding in some conditions suggested that stimulus disparity was reduced. Experiment 3 clarified those results and extended the finding that the acquisition of operant discrimination closely parallels extinction of responding in S(Delta). In sum, it appears that higher reinforcement rates and longer S(Delta) exposure facilitate the acquisition of discriminated operant responding.     

Do Conflict Resolution and Recovery Predict the Survival of Adolescents' Romantic Relationships?

Numerous studies have shown that being able to resolve and recover from conflicts is of key importance for relationship satisfaction and stability in adults. Less is known about the importance of these relationship dynamics in adolescent romantic relationships. Therefore, this study investigated whether conflict resolution and recovery predict breakups in middle adolescent couples. Couples who are able to resolve and recover from conflict were expected to demonstrate a lower probability of breaking up. In total, 80 adolescent couples (M age = 15.48, SD = 1.16) participated in a 4-wave prospective questionnaire and observational study, with one year between measurements. In addition to self-report measures, adolescents were observed in real-time during conflicts with their partners. Multilevel Proportional Hazard analyses revealed that, contrary to the hypothesis, conflict resolution and conflict recovery did not predict the likelihood of breakup. Survival differences were not attributable to conflict resolution or conflict recovery. More research is needed to consider the unique relationship factors of adolescent romantic relationships to determine why some relationships survive while others do not.     

Properties of an Inward-Facing State of LeuT: Conformational Stability and?Substrate Release

The leucine transporter (LeuT) is a bacterial homolog of the human monoamine transporters, which are important pharmaceutical targets. There are no high-resolution structures of the human transporters available; however, LeuT has been crystallized in several different conformational states. Recently, an inward-facing conformation of LeuT was solved revealing an unexpectedly large movement of transmembrane helix 1a (TM1a). We have performed molecular dynamics simulations of the mutated and wild-type transporter, with and without the cocrystallized Fab antibody fragment, to investigate the properties of this inward-facing conformation in relation to transport by LeuT within the membrane environment. In all of the simulations, local conformational changes with respect to the crystal structure are consistently observed, especially in TM1a. Umbrella sampling revealed a soft potential for TM1a tilting. Furthermore, simulations of inward-facing LeuT with Na⁺ ions and substrate bound suggest that one of the Na⁺ ion binding sites is fully disrupted. Release of alanine and the second Na⁺ ion is also observed, giving insight into the final stage of the translocation process in atomistic detail.     

Phosphorus Biogeochemistry and the Impact of Phosphorus Enrichment: Why Is the Everglades so Unique?

The Florida Everglades is extremely oligotrophic and sensitive to small increases in phosphorus (P) concentrations. P enrichment is one of the dominant anthropogenic impacts on the ecosystem and is therefore a main focus of restoration efforts. In this review, we synthesize research on P biogeochemistry and the impact of P enrichment on ecosystem structure and function in the Florida Everglades. There are clear patterns of increased P concentrations and altered structure and processes along nutrient-enrichment gradients in the water, periphyton, soils, macrophytes, and consumers. Periphyton, an assemblage of algae, bacteria, and associated microfauna, is abundant and has a large influence on phosphorus cycling in the Everglades. The oligotrophic Everglades is P-starved, has lower P concentrations and higher nitrogen–phosphorus (N:P) ratios, and has oxidized to only slightly reduced soil profiles compared to other freshwater wetland ecosystems. Possible general causes and indications of P limitation in the Everglades and other wetlands include geology, hydrology, and dominance of oxidative microbial nutrient cycling. The Everglades may be unique with respect to P biogeochemistry because of the multiple causes of P limitation and the resulting high degree of limitation. Received 23 August 2000; Accepted 23 March 2001.     

Preparation and Characterization of Gas-filled Liposomes: Can They Improve Oil Recovery?

Although well known for delivering various pharmaceutical agents, liposomes can be prepared to entrap gas rather than aqueous media and have the potential to be used as pressure probes in magnetic resonance imaging (MRI). Using these gas-filled liposomes (GFL) as tracers, MRI imaging of pressure regions of a fluid flowing through a porous medium could be established. This knowledge can be exploited to enhance recovery of oil from the porous rock regions within oil fields. In the preliminary studies, we have optimized the lipid composition of GFL prepared using a simple homogenization technique and investigated key physico-chemical characteristics (size and the physical stability) and their efficacy as pressure probes. In contrast to the liposomes possessing an aqueous core which are prepared at temperatures above their phase transition temperature (T_c), homogenization of the phospholipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocoline (DSPC) in aqueous medium below their T_c was found to be crucial in formation of stable GFL. DSPC based preparations yielded a GFL volume of more than five times compared to their DPPC counter part. Although the initial vesicle sizes of both DSPC and DPPC based GFL were about 10 μm, after 7 days storage at 25°C, the vesicle sizes of both formulations significantly (p < 0.05) increased to 28.3 ± 0.3 μm and 12.3 ± 1.0 μm, respectively. When the DPPC preparation was supplemented with cholesterol at a 1:0.5 or 1:1 molar ratio, significantly (p < 0.05) larger vesicles were formed (12–13 μm), however, compared to DPPC only vesicles, both cholesterol supplemented formulations displayed enhanced stability on storage indicating a stabilizing effect of cholesterol on these gas-filled vesicles. In order to induce surface charge on the GFL, DPPC and cholesterol (1: 0.5 molar ratio) liposomes were supplemented with a cationic surfactant, stearylamine, at a molar ratio of 0.25 or 0.125. Interestingly, the ζ potential values remained around neutrality at both stearylamine ratios suggesting the cationic surfactant was not incorporated within the bilayers of the GFL. Microscopic analysis of GFL confirmed the presence of spherical structures with a size distribution between 1–8 μm. This study has identified that DSPC based GFL in aqueous medium dispersed in 2% w/v methyl cellulose although yielded higher vesicle sizes over time were most stable under high pressures exerted in MRI.